The invention herein disclosed was made in the course of or under a contract or subcontract thereunder with the Department of the Navy.
The present invention relates to semiconductor light emitting diodes and more specifically to light emitting diodes having a low beam divergence.
Semiconductor light emitting diodes (LED) in general, are bodies of single crystalline semiconductor material which when biased, emit incoherent light, through the recombination of pairs of oppositely charged carriers. Typically, the light generated in a light emitting diode is near the P-N junction plane and light that is generated propagates uniformly in all directions. In viewing such light emitting diodes from either an edge or a surface, the emission of the light appears uniform in all directions. This light emission is referred to by those skilled in the art as Lambertion. The divergence of a Lambertion light beam is such that the full width at half the maxium of the optical intensity, referred to as FWHM, is 120.degree. C.
In a field such as optical communications, where light emitting diodes are coupled into light transmission pipes, such as an optical fiber, it becomes critical that the beam divergence of the light emitted from the LED be as narrow as possible for the efficient coupling of the generated light into the fiber. Thus, it would be most desirable in fields utilizing light emitting diodes, that the beam divergence be small.